Help with Texture fade out
You can use the node setup at the bottom of the following images and keyframe the Mix Shader's Fac: value from 0-1. Obviously load one image into one node and another into the other node.

Fac: at 0, notepad showing:



Fac: at 1, bricks showing:



If you wish, the pictured .blend file with the nodes can be downloaded right here:



If you want to fade into a Diffuse BSDF, just don't include one of the Image Textures and still keyframe the same value.

Fac: at 0, notepad showing:



Fac: at 1, Diffuse BSDF showing: